Pumps for high vapor pressure liquids



June 17, 1958 H. c. MAYO PUMPS FOR HIGH VAPOR PRESSURE LIQUIDS Filed July 12, 1956 INVENTOR.

HAYS C. MAYO AKQLQQW UZYBW ATTORNEYS UnitedStates Patent 0.

PUMPS FOR HIGH VAPOR PRESSURE LIQUIDS Hays C. Mayo, Bayside, N. Y., assignor to The M. W. Kellogg Company, Jersey City, N. 1., a corporation of Delaware Application July 12, 1956, Serial No. 597,369 8 Claims. cr es-s7 'Thisinvention relates to pumps and particularly to pumps'used in handling high vapor pressure liquids.

' Thepumping of high vapor pressure liquids and especially thelow temperature pumping of high vapor pressure liquids, such as ethylene, propylene, methane, and the like, at 10 F. and lower, presents a serious problem byreason of the difiiculties encountered in sealing the pump drive connection against leakage of the material handledj Leakage not only results in reduced pumping efficiency anda substantial money loss due to material loss but with highly volatile inflammable materials of the character specifically referred to, presents a real hazard from fire. Many attempts have been made to solve this problem. The more successful solutions involve complicated and expensive sealing systems which require constant attention and adjustment. At best seal failure is always possible so that the fire hazard remains.

I have, found a simple and practical way of solving this problem which eliminates all fire hazard and product loss. I

It is a principal object of this invention to provide a simple; eflicient and cheap arrangement for completely eliminating product leakage in pumping high vapor pressure liquids and its attendant losses and hazards.

:It is also a principal object of this invention to provide a system for pumping high vapor pressure liquids in which no effort is made to mechanically seal the pump drive connection butleakage is eliminated by generating apressure effective on said connection which opposes the pressure tending to cause'the leakage.

It is an "additional principalobject of the invention to provide a leakproof system, for pumping high vapor pressure "liquids at low temperature in which the pump drive connection and the pump drive motor are housed in a pressure vessel, 'the pump space being. in comparatively free communication with the vessel space so that the liquid handled may pass thereinto, and heat is supplied in the vessel space to vaporize the liquid in amount sufficient to generate a high enough pressure to prevent the level of liquid in said vessel space exceeding a predetermined level. i

'Thefurther objects, features and advantages of the invention will become apparent from a consideration of the following detailed description taken with the accompanying drawings in which the single figure is a sectional view illustrating a present preferred embodiment of the invention.

The invention is of general application and may be applied to systems for pumping liquids whose vapor pressure at or below the maximum safe operating temperature of the electric motor employed for driving the pumpof the system, is above the pump suction pressure. The invention is particularly applicable to the pumping of low boiling point hydrocarbon materials such as ethylene, propylene, methane, etc., and particularly to the pumping of these materials at reduced temperatures in the order of -l,"and lower.

2,839,006 Patented June 17, 1958 In its broader aspects the invention involves the provision of a pressure container which houses the pump drive motor and surrounds the portion of the pump casing through which the motor shaft passes into the pump. No special effort is made to seal the joint at the pump casing and motor shaft so that the liquid pumped may leak therethrough into the pressure casing. Con trolled heating means are provided within the casing so that when the leaking pumped liquid reaches a predetermined level it will come under the influence of the heating means to be heated and evaporated thereby, thus raising the pressure within the pressure casing until it evaporatedto augment the pressure, ultimately a steady state or equilibrium condition is attained. The leakage path may be connected directly by a suitable passageway to the high pressure side of the'pump so that on raising of the pressure in the chamber above the pump outlet pressure, excess liquid will be forced back into the pump outlet. In this case the liquid pumped musthave a boiling temperature lower than the safe operative motor temperature at the pump outlet pressure. Alternately, the leakage path may be connected to the pump inlet so that the liquid forced out of the pressure chamber will flow to the pump inlet. In this arrangement the liquid handled need have a boiling point equal to or less than the safe operating pump temperature at the pump suction pressure. The manner of carrying out the invention in practice is shown in the drawings .and specific reference is had thereto.

The pump 10 is of conventional design and includes a rotor 11 for acting upon the liquid supplied through the inlet 12 to increase its pressure to the desired value at the outlet 13 The pump 10 includes an upper casing 14 through which the shaft 15 passes. The shaft 15 mounts the rotor 11. The shaft 15 includes a bearing sleeve 16 which extends through an upper throttle bushing 17 and alower throttle bushing 18. The bushings 17 and 18 are mounted on a thimble 19 which extends into a bore in the casing 14 and is fastened relative thereto by a circular series of boltsor other conventional fastening means. The thimble 19' is surrounded by a ring 20 which is fastened to the casing 14 also by a circular series of bolts or other conventional fastening means. Thelower end of. a cylindrical casing 21 surrounds the ring 20 and is fastened thereto as by a circular series of screw bolts. A suitable gasket 22 may be employed to assure the sealing of the space within the chamber 21 from the free space therearound.

-The cylindrical casing 21 includes a diaphragm 23 adjacent its lower end. The diaphragm 23 may include a middle insulation section 24. The shaft 15 passes loosely through an aperture in the center of the diaphragm 23. The inner edge of the diaphragm 23 may have a ring barrier member 25 attached thereto so that a predetermined depth of the liquid pumped may be maintained above the diaphragm23 at the level of the ring 25. Shaft 15 carries a slinger 26 which is adapted to pick up liquid coming up along theshaft l5 and slings it outwardly against the heating coils 27 on the internal wall of the section 21. The heating coils 27 may house an elongated electrical heating element which is thermostatically controlled to maintain a predetermined temperature within the upper end of the casing, said predetermined temperature being at or below the safe operating temperature of motor 30. .Alternately, the coils 27 may circulate a liquid or vaporized heating medium supplied. from a suitable source thereof and controlled through a thermostatically controlled valve, not shown, to maintain a predetermined temperature Within the upper end of the casing 21. In place of the coils ZTajacket may beemployed and the circulation of a heating medium: therethrough controlled for the purposes stated.

The upper end of the casing 21 includes a handhole defining member 31 which is normally sealed by a suitable cover 32. In the region of the handhole 31 is a cow pling 33 of conventional construction through which the shaft 34 of the motor 30 is coupled to the shaft 15. The

casing 21 has an outwardly extending flange 35 united.

thereto upon which is mounted the motor 30. The motor 30 is preferably a standard open motor since an explosion-proof motor is not required as the atmosphere is excluded therefrom by the casing 21 and the motor container 37. The flange 36 which is integrally connected to the motorcontainer 37 and is also positioned on the flange 35; the flanges 35 and 36 areunited in any conventional manner as by a circular series of. bolts. Suitable gasket material may be interposed between the flanges 35 and 36 to assure a leakproof joint. casing 37 is closed at its upper end by a disc cover 38. Cooling coils 39, or a jacket, not shown, are provided through which water or similar suitable cooling medium may be circulated, at arate sufficieut to remove the heat generated by the motor so that it may be maintained at or below its safe maximum temperature. The casing 21 I may include a tapped hole adjacent its lower end to receive the tapped end of the line 40 which leads the pump leakage liquid. from the lower end of the casing 21 to the top of the supply container thereof (not shown). In lieu of the line 40 a pasageway 41 may be provided which communicates the pump inlet to the space between the lower throttle bushing 18 and the upper throttle bushing 17'. When the passageway 41 is em: ployed, liquid will flow from the lower end of the casing 21 into the pump inlet.

When the pump is set into operation the liquid to be pumped, 'as for instance, ethylene, propylene, methane, etc., is supplied from the supply container thereof, not shown, at a pressure of about 10 p. s. i. g. and at a temperature of about l. The rotor 11 is rotated at the proper speed through the motor 30 and the shaft 15 to receive the liquid from the inlet 12 and circulates it to the outlet 13 so that it will exit from the pump at a pressure of about 70 p. s. i. g. and a temperature of 10.". In the region where the pump shaft passes through the pump outlet passageway the liquid pumped is at substantially maximum pressure and will thus tend to flow along the shaft 15 and outwardly of the casing 14. With the passageway 41 provided, some of the leaking liquid will be returned to pump inlet passageway 12. However, there will still be a pressure differential between the suctionvpressure and the external pressure so that the liquid pumped will move along between the shaft 15 and the upper throttle bushing 17 into the lower end of the casing 21. As the pumping action continues the level of the leaking liquid will raise until it passes the diaphragm 23 and reaches the slinger 26 at which time it will be thrown against the coils 27 to be vaporized thereat. The heating and vaporization of the liquid will continue until the heat absorbed by the liquid causes sufficient vaporization of the liquid to raise the pressure within the casing 21 to the point that it will overcome the pressure differential causing liquid flow into the container 21. The vaporization of liquid will go beyond that required merely to balance the pressure to the point where a pressure differential is set up tending to force the-liquid in reverse from the chamber 21 into the pump inlet 12 or if the line is employed, through the line 40 back to the liquid supply container. The vaporized liquid will ultimately be insufiicient to prevent leakage so that further liquid will enter the cas- The.

.4 a ing 21 to be vaporized thereat. This'procedure will repeat itself until a substantial steady state or equilibrium. is obtained for any set of conditions of suction, pressure, temperature, and pump operation.

Since many changes may be made without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not limitative.

I claim:

1. A pump system comprising a pump havinga casing provided with an inlet side and an outlctjside,.arotary pumping element in said casing adapted to receive liquid from said inlet side under inlet pressure and transfer it to said outlet side. at an augmented outlet pressure, a shaft mounting said rotary pumping element, journal means in said casing, said shaft extending through said journal means and outwardly of said casing, an electric motor connected to said shaft to drivesaid shaftand said rotor element, a pressure tight container connected to said pump casing and housing said'motor and the extending end of said shaft, said motor in open communication with the full length of said container, and heating; means in said container positioned adjacent the pump. end thereof and adapted to be contacted by liquid leaking out through said journal means when the liquidreaches the levelofsaid heating means to vaporize said leakin -liquid tomaintain a pressure throughout said container at least equal to the pressure effective to cause the leakage.

2. A pump systemcomprising a pump having a casingv provided with an inlet side and an outlet side, a rotary pumping element in said casing adapted to receive liquid from said inlet side under inlet pressure and transfer it to said outlet side at an augmented outlet pressure, a shaft mounting said rotary pumping element, journal means in said casing, said shaft extending through said journal means and outwardly of said casing, an electric motor connected to said shaft to drive said shaft and said rotor element, a pressure tight container connected. to said pump casing and housing said motor andthe extending end of said shaft, said motor in open communicationwith the full length of said container, heating means in said container positioned adjacent the pump end thereof and adapted to be contacted by liquid leaking. out through said journal means when the liquid reaches the level of said heating means to vaporize said leakingv liquid tomaintain a pressure throughout said container at least equal to the pressure effective to cause the leakage, andheat exchangc means in said pump casing positioned adjacent said motor adapted to remove heat generated by said motor to main-. tain said motor within its safe operating, temperature range. I

3. A pump system comprising a pump having a casing provided with an inlet side and an outlet side, a rotary pumping element in said casing adapted to. receive liquid from said inlet side under inlet pressure and transferitto said outlet side at an augmented outlet pressure, a shaft mounting said rotary pumping element, journal means in said casing, said shaft extending through said journal means and outwardly of said casing, an electric motor spaced from said casing and connected to said shaft to drive said. shaft and said rotor element, a pressure tight container connected to said pump casing and housing said motor and the extending end of said shaft, means carried by said shaft adapted to be contacted by liquid leaking into said container along said shaft and throw it outwardly towards the walls of said container, heating means in said container adapted to be contacted by liquid thrown outwardly by said carried means thereby to vaporize said thrown out liquid to maintain a pressure in said container at least equal to the pressure effective to'cause'the leakage, and heat exchange means in said pump casing positioned adjacent said motor adapted to remove heat generated by said motor to maintain said motorwithin its safe operating temperature range: i

4. A pump system comprising a pump having a casing provided with an inlet side and an outlet side, a rotary pumping element in said casing adapted to receive liquid from said inlet side under inlet pressure and transfer it to said outlet side at an augmented outlet pressure, a shaft mounting said rotary pumping element, journal means in said casing, said shaft extending through said journal means and outwardly of said casing, an electric motor spaced from said casing and connected to said shaft to drive said shaft and said rotor element, a pressure tight container connected to said pump casing and housing said motor and the extending and of said shaft, a slinger carried by said shaft adapted to be contacted by liquid leaking into said container along said shaft and throw it outwardly towards the walls of said container, a heating coil in said container adjacent the Walls thereof and positioned to be contacted by liquid thrown outwardly by said slinger to vaporize said thrown out liquid to maintain a pressure in said container at least equal to the pressure effective to cause the leakage, and heat exchange means in said pump casing positioned adjacent said motor adapted to remove heat generated. by said motor to maintain said motor within its safe operating temperature range.

5. A pump system comprising .a pump having a casing provided with an inlet side and an outlet side, a rotary pumping element in said casing adapted to receive liquid from said inlet side under inlet pressure and transfer it to said outlet side at an augmented outlet pressure, a shaft mounting said rotary pumping element, journal means in said casing, said shaft extending through said journal means and outwardly of said casing, an electric motor spaced from said casing and connected to said shaft to drive said shaft and said rotor element, a pressure tight container connected to said pump casing and housing said motor and the extending end of said shaft, a transverse diaphragm in said casing having a central hole through which said shaft passes, a slinger carried by said shaft outwardly of said diaphragm adapted to be contacted by liquid leaking into said container along said shaft and throw said liquid towards the Walls of said container, an upstanding lip at said central hole to retain a predetermined depth of liquid on said diaphragm, a heating coil in said container adjacent the walls thereof and positioned immediately outwardly of said diaphragm to be contacted by liquid thrown outwardlyby said slinger to vaporize said thrown out liquid to maintain a pressure in said container at least equal to the pressure effective to cause the leakage, and heat exchange means in said pump casing positioned adjacent said motor adapted to remove heat generated by said motor to maintain said motor within its safe operating temperature range.

6. A pump system comprising a pump having a casing provided with an inlet side and an outlet side, a rotary pumping element in said casing adapted to receive liquid from said inlet side under inlet pressure and transfer it to said outlet side at an augmented outlet pressure, a shaft mounting said rotary pumping element, journal means in said casing, said shaft extending through said journal means and outwardly of said casing, an electric motor spaced from said casing and connected to said shaft to drive said shaft and said rotor element, a pressure tight container connected to said pump casing and housing said motor and the extending end of said shaft, a slinger carried by said shaft adapted'to be contacted by liquid leaking into said container along said shaft and throw it towards the walls of said container, a heating coil in said container adjacent the walls thereof and positioned to be contacted by liquid thrown outwardly by said slinger to vaporize said thrown out liquid to maintain a pressure in said container at least equal to the pressure effective to cause the leakage, heat exchange means in said pump casing positioned adjacent said motor adapted to remove heat generated by said motor to maintain said motor within its safe operating temperature range, and means for removal of liquid from said container.

7. A pump system comprising a pump having a casing provided with an inlet side and an outlet side, a rotary pumping element in said casing adapted to receive liquid from said inlet side under inlet pressure and transfer it to said outlet side at an augmented outlet pressure, a shaft mounting said rotary pumping element, journal means in said casing, said shaft extending through said journal means and outwardly of said casing, an electric motor spaced from said casing and connected to said shaft to drive said shaft and said rotor element, a pressure tight container connected to said pump casing and housing said motor and the extending end of said shaft, a slinger carried by said shaft adapted to be contacted by liquid leaking into said container along said shaft and throw it towards the walls of said container, a heating coil in said container adjacent the walls thereof and positioned to be contacted by liquid thrown outwardly by said slinger to vaporize said thrown out liquid to maintain a pressure in said container at least equal to the pressure effective to cause the leakage, heat exchange means in said pump casing positioned adjacent said motor adapted to remove heat generated by said motor to maintain said motor within its safe operating temperature range, and a passageway communicating the journal and shaft interface to one of said sides.

8. A pump system comprising a pump having a casing provided with an inlet side and an outlet side, a rotary pumping element in said casing adapted to receive liquid from said inlet side under inlet pressure and transfer it to said outlet side at an augmented outlet pressure, a shaft mounting said rotary pumping element, journal means in said casing, said shaft extending through said journal means and outwardly of said casing, an electric motor spaced from said casing and connected to said shaft to drive said shaft and said rotor element, a pressure tight container connected to said pump casing and housing said motor and the extending end of said shaft, a slinger carried by said shaft adapted to be contacted by liquid leaking into said container along said shaft and throw it towards the walls of said container, a heating coil in said container adjacent the walls thereof and positioned to be contacted by liquid thrown outwardly by said slinger to vaporize said thrown out liquid to maintain a pressure in said container at least equal to the pressure effective to cause the leakage, heat exchange means in said pump casing positioned adjacent said motor adapted to remove heat generated by said motor to maintain said motor within its safe operating temperature range, and a passageway communicating the journal and shaft interface to said inlet for flow of liquid from said container thereinto.

References Cited in the file of this patent UNITED STATES PATENTS 2,157,424 Myers et al. May 9, 1939 2,468,187 Ericson Apr. 26, 1949 2,764,943 Peters Oct. 2, 1956 

